Obesity is a disease that occurs when a person carries excess weight or body fat that could affect their health. A doctor will usually suggest that a person is obese if they have a high body mass index.

The Body Mass Index (BMI) is a tool that doctors can use to assess whether a person is of an appropriate weight for their age, gender, and height. The measurement combines height and weight.

A BMI between 25 and 29.9 indicates that a person is overweight. A BMI of 30 or more suggests that a person may have obesity.

Other factors such as the waist to hip ratio (WHR), the waist to height ratio (WtHR), and the amount and distribution of fat on the body also play a role in determining the weight and health of a person's body shape.

When a person is obese and overweight, it can increase their risk of developing a number of health conditions, including metabolic syndrome, arthritis, and some types of cancer.

Metabolic syndrome encompasses a number of issues such as high blood pressure, type 2 diabetes, and cardiovascular disease.

Maintaining a healthy weight or losing weight through diet and exercise is one way to prevent or reduce obesity. In some cases, a person may need surgery.

Now read on to find out why obesity occurs.

1) Consume too many calories

When a person is consuming more calories than they are consuming for energy, their body stores the extra calories as fat. This can lead to overweight and obesity.

Also, some types of foods are more likely to make you gain weight, especially those high in fats and sugars.

Foods that increase your risk of weight gain include:

• Fast food
• fried foods such as french fries
• fatty and processed meat
• lots of dairy products
• Foods with added sugar such as baked goods, ready-made breakfast cereals, and cookies
• Foods that contain hidden sugars, such as ketchup and many other canned and packaged foods
• sweetened juices, lemonades and alcoholic beverages
• processed, high-carbohydrate foods like bread and bagels
• Some processed foods contain high fructose corn syrup as a sweetener, including savory products like ketchup.

Eating too much of these foods and too little exercise can lead to weight gain and obesity.

A person on a diet consisting primarily of fruits, vegetables, whole grains, and water is still at risk of gaining excess weight if they overeat or if, for example, genetic factors increase their risk.

However, they are more likely to have a varied diet while maintaining a healthy weight. Fresh foods and whole grains contain fiber, which makes a person feel full longer and promotes healthy digestion.

2) Lead a sedentary lifestyle

Many people lead a much more sedentary lifestyle than their parents and grandparents.

Examples of sedentary habits are:

• work in an office instead of doing manual labor
• Play games on a computer instead of engaging in physical activity outside
• drive to places instead of walking or cycling
• The less a person moves, the fewer calories they burn.
• In addition, physical activity affects how a person's hormones work, and hormones affect how the body processes food.
• Several studies have shown that physical activity can help keep insulin levels stable, and that unstable insulin levels can lead to weight gain.

Researchers who published a report in BMJ Open Sport and Exercise Medicine in 2017 found that the designs of some studies make it difficult to draw precise conclusions: "A lifestyle that included regular [physical activity] has become a key factor in maintaining it and improving many aspects of health, including insulin sensitivity. "

Physical activity doesn't have to be done in the gym. Physical work, walking or cycling, climbing stairs, and household chores all contribute to this.

However, the type and intensity of activity can affect the extent to which it benefits the body in the short and long term.

3) Not getting enough sleep

Research has shown that a lack of sleep increases the risk of weight gain and developing obesity.

The researchers reviewed evidence from over 28,000 children and 15,000 adults in the UK from 1977 to 2012. In 2012, they concluded that sleep deprivation significantly increased the risk of obesity in both adults and children.

The changes affected children as young as 5 years old.

The team suggested that sleep deprivation can lead to obesity as it can lead to hormonal changes that increase appetite.

When a person doesn't get enough sleep, their body makes ghrelin, a hormone that stimulates appetite. At the same time, a lack of sleep also leads to lower production of leptin, a hormone that suppresses appetite.

4) Endocrine Disruptors

A team from the University of Barcelona published a study in the World Journal of Gastroenterology that suggests how liquid fructose - a type of sugar - in beverages can alter lipid metabolism and lead to fatty liver and metabolic syndrome.

Metabolic syndrome features include diabetes, cardiovascular disease, and high blood pressure. Obese people are more likely to have metabolic syndrome.

After feeding the rats a 10 percent fructose solution for 14 days, the scientists found that their metabolism gradually changed.

Scientists believe there is a link between high fructose consumption and obesity and metabolic syndrome. Authorities have raised concerns about using high-fructose corn syrup to sweeten beverages and other foods.

Animal studies have shown that obesity due to fructose consumption is also closely related to type 2 diabetes.

In 2018, the researchers published the results of studies on young rats. They too experienced metabolic changes, oxidative stress and inflammation after consuming fructose syrup.

The researchers state that "increased fructose intake may be an important predictor of metabolic risk in young people".

They are calling for changes in young people's diets to prevent these problems.

Avoid high fructose corn syrup

Foods that contain high fructose corn syrup include:

• Lemonades, energy drinks and sports drinks
• Candy and ice cream
• Coffee cream
• Sauces and condiments, including salad dressings, ketchup and barbecue sauce
• sweetened foods like yogurt, juices, and canned foods
• Bread and other ready-made baked goods
• Breakfast cereals, granola bars, and energy or nutritional bars
• How to reduce your intake of corn syrup and other additives:
• Check the labels before buying
• If possible, opt for unsweetened or less processed items
• Prepare salad dressings and bake other products at home
• Some foods contain other sweeteners, but these can also have adverse effects.

5) Medication and weight gain

Some medications can also cause weight gain.

The results of a review and meta-analysis published in the Journal of Clinical Endocrinology and Metabolism in 2015 found that some drugs caused people to gain weight over a period of months.

• atypical antipsychotics, especially olanzapine, quetiapine, and risperidone
• Anticonvulsants and mood stabilizers, especially gabapentin
• hypoglycemic drugs such as tolbutamide
• Glucocorticoids, used to treat rheumatoid arthritis
• some antidepressants

However, some drugs can cause weight loss. Anyone taking a new drug and worried about their weight should ask their doctor whether the drug is likely to have an impact on their weight.

6) Is Obesity Self-Persistent?

The longer a person is overweight, the more difficult it can be for them to lose weight.

The results of a mouse study published in the journal Nature Communications in 2015 suggest that the more fat a person carries, the less likely the body is to burn fat due to a protein or gene known as sLR11.

It seems that the more fat a person has, the more SLR11 their body will produce. The protein blocks the body's ability to burn fat, making it harder to lose the extra weight.

7) Obesity gene

A faulty gene known as the fat mass and obesity-associated gene (FTO) is responsible for some cases of obesity.

A study published in 2013 suggests a link between this gene and:

• obesity
• Behaviors That Lead to Obesity
• higher food intake
• a preference for high calorie foods
• an impaired ability to feel full known as satiety

The hormone ghrelin plays a crucial role in eating behavior. Among other things, ghrelin affects the release of growth hormones and the way the body accumulates fat.

The activity of the FTO gene can affect a person's likelihood of suffering from obesity as it affects the amount of ghrelin a person has.

In a study of 250 people with eating disorders published in Plos One in 2017, the researchers suggested that aspects of the FTO could also play a role in conditions such as binge eating and emotional eating.